车身薄壁梁结构轻量化设计的理论研究

薄壁梁是车身骨架结构的基本承载单元.为研究车身轻量化对其刚度的影响,首先推导了两端固支梁的静态弯曲和扭转刚度表达式.为获取最佳截面的轻型结构,分别研究了薄壁梁的截面尺寸和壁厚等几何参数对其刚度/质量比的影响.分析了用轻质材料替代传统钢材对其刚度和结构尺寸的影响.对开环与闭环截面梁的刚度/质量比进行了比较.分别找出了能显著影响上述薄壁梁的弯曲和扭转刚度的几何和材料参数.提出了获得高刚度车身典型薄壁梁的轻量化设计原则.

Theoretical study on lightweight design of thin-walled beam structure for automobile body

The main load-supporting elements for an automobile framework are thin-walled beams. To study the effectiveness of lightweighting on the body stiffness, the analytical formulae describing static bending and torsional stiffness of a beam with fixed-fixed supporters were derived firstly. To get a light thin-walled beam structure with optimum section, the influence of every sectional geometry parameter on the stiffness-mass ratio was discussed respectively. After replacing the steel by the lightweight material, the corresponding variations in structural stiffness and size were analyzed. The stiffness-mass ratios of beams with open and close loop sections were also compared with each other. Finally, a few geometrical and material parameters, which can greatly influence the bending or torsional stiffness of these thin-walled beams, were found out. For a typical thin-walled beam applied in an automobile body, the design guideline achieving both lightweight and high stiffness is presented.